1. Field of the Invention
The present invention relates to a thin film magnetic head having at least inductive magnetic transducer for writing and a method of manufacturing thereof.
2. Description of the Related Art
Recently, an improvement in performance of a thin film magnetic head has been sought in accordance with an increase in a surface recording density of a hard disk or the like. A composite thin film magnetic head, which has a stacked structure comprising a recording head having an inductive magnetic transducer and a reproducing head having a magnetoresistive (hereinafter referred to as MR) element that is a type of magnetic transducer, is widely used as the thin film magnetic head.
The recording head comprises, for example, a top magnetic pole (top pole) and a bottom magnetic pole (bottom pole) which are located respectively at the top side and the bottom side of a write gap and a coil for generating a magnetic flux which is surrounded by an insulating layer and located between the top and bottom poles. The top and bottom poles respectively have areas with a uniform width near the region of the write gap close to a recording-medium opposite surface (air bearing surface) facing a magnetic recording medium (hereinafter referred to as a xe2x80x98recording mediumxe2x80x99), and these areas constitute a xe2x80x98magnetic pole tipxe2x80x99 which defines a record track width.
In order to improve a recording density among performances of the recording head, it is necessary to greatly reduce the width of the magnetic pole tip (magnetic pole width) to a submicron order and to increase a track density of a recording medium. In such a case, it is desirable that the magnetic pole width throughout the magnetic pole tip is constant with high accuracy. It is because a partially large magnetic pole width causes side erase phenomenon that writing is performed not only to a track area to be written but also to the adjacent track area, and the information already written in the adjoining track area will be overwritten and eliminated.
Thus, as the magnetic pole width decrease to a highly minute level, there is a more need for decreasing the thickness of the magnetic pole itself because of manufacturing requirements, and sizes of all the composition parts (for example, a coil) of the entire head tend to decrease to a highly minute level In order to maintain the excellent characteristic of overwriting information to the recording medium among the performances of the recording head, it is necessary to generate a sufficient quantity of magnetic flux by energizing the coil and to supply the generated magnetic flux to the magnetic pole portions. However, as a result of the trend of highly decreasing the size of the above-described composition parts, if the cross-section area of the coil is too small, the electric resistance value will become too large, amount of current flowing through the coil will decrease, and the amount of the generated magnetic flux will decrease remarkably, which is a problem. The reduction amount of the generated magnetic flux may cause a deficient magnetic flux for magnetizing the recording medium during recording information and a very poor overwriting characteristic.
The present invention has been achieved in view of the above problems. It is an object of the invention to provide a thin film magnetic head comprising a magnetic pole with a minute width and an excellent overwriting characteristic, and a method of manufacturing thereof.
A thin film magnetic head of the invention comprises a first magnetic layer and a second magnetic layer magnetically coupled to each other and having two magnetic poles facing each other with a gap layer in between near and in a recording-medium-facing surface to be faced with a recording medium; a thin film coil provided between the first and second magnetic layers; and an insulating layer for insulating the thin film coil from the first and the second magnetic layers, the first magnetic layer including a laminate of a first magnetic layer portion and a second magnetic layer portion, the first magnetic layer portion being located away from the gap layer and the second magnetic layer portion being located close to the gap layer, the second magnetic layer portion extending adjacent to the gap layer from the recording-medium-facing surface to a first position while maintaining a uniform width for defining a write track width on the recording medium, the first magnetic layer portion including a uniform width portion and a widened portion, the uniform width portion extending from the recording-medium-facing surface or its neighborhood to a second position located at or near the first position, while maintaining the same width as the uniform width of the second magnetic layer portion, the widened portion extending from the second position to a third position and having a width greater than that of the uniform width portion, wherein the thin film coil comprises a first thin film coil, most of the first thin film being included in a space defined by a thickness of the uniform width portion in the first magnetic layer portion, and the insulating layer comprises a first insulating layer portion located in a space defined by a thickness of the second magnetic layer portion and being in contact with the first thin film coil.
According to the thin film magnetic head of the invention, the thin film coil comprises the first thin film coil located so that most thereof may be included in the space defined by the thickness of the uniform width portion in the first magnetic layer portion, and the insulating layer comprises the first insulating layer portion located in a space defined by the thickness of the second magnetic layer portion and being in contact with the first thin film coil. Since the first thin film coil is located to be in contact with the first insulating layer portion, the thickness of the first thin film coil can be determined properly and independently from the thickness of the first insulating layer portion, compared to a head where a thin film coil is located in a space defined by the thickness of the second magnetic layer portion.
In the thin film magnetic head of the intention, a thickness of the first magnetic layer portion may be larger than the thickness of the first thin film coil.
In the thin film magnetic head of the invention, the thickness of the second magnetic layer portion may be 1.0 micron or less.
In the thin film magnetic head of the invention, an approximal surface of the first insulating layer portion in contact with the first thin film coil may be coplanar with a boundary surface between the first magnetic layer portion and the second magnetic layer portion.
In the thin film magnetic head of the invention, when the third position in the first magnetic layer portion is located between the recording-medium-facing surface and the thin film coil and the insulating layer further comprises a second insulating layer portion covering the first thin film coil, a first surface of the second insulating layer portion, the first surface being far from the first insulating layer portion may be coplanar with a second surface of the first magnetic layer portion, the second surface being far from the second magnetic layer portion.
In the thin film magnetic head of the invention, when the first magnetic layer further comprises a third magnetic layer portion partially overlapping and magnetically coupled to the first magnetic layer portion, a part of the first insulating layer portion may be located in an overlap area where the first magnetic layer portion and the third magnetic layer portion are overlapping each other.
In the thin film magnetic head of the invention, when the thin film coil further comprises a second thin film coil electrically connected with the first thin film coil and the first magnetic layer further comprises a fourth magnetic layer portion for connecting magnetically the first magnetic layer portion with the third magnetic layer portion, the second thin film coil may be located in a manner that most of the second thin film is included in a space defined by a thickness of the fourth magnetic layer portion.
In the thin film magnetic head of the invention, a recessed area is provided on an opposite side surface of the first insulating layer portion from the gap layer, and the first thin film coil may be located in the recessed area.
In the thin film magnetic head of the invention, the first insulating layer may be in contact with the second magnetic layer portion at the first position. In such a case, it is preferable that a boundary surface between the second magnetic layer portion and the first insulating layer portion is a plane and the boundary surface between the second magnetic layer portion and the first insulating layer portion is perpendicular to a direction in which the second magnetic layer portion extends.
In the thin film magnetic head of the invention, a magnetic material of the second magnetic layer portion may have a saturation magnetic flux density being equal to or higher than that of a magnetic material of the first magnetic layer portion. In such a case, it is preferred that the first magnetic layer portion is made of a magnetic material containing iron, nickel and cobalt, and the second magnetic layer portion is made of a magnetic material containing either a nickel-iron alloy or a cobalt-iron alloy.
In the thin film magnetic head of the invention, at least one of the first magnetic layer portion, the second magnetic layer portion, and the second magnetic layer may be made of a magnetic material containing iron nitride, a nickel-iron alloy or an amorphous alloy. It is preferred that the amorphous alloy is a cobalt-iron alloy, a zirconium-cobalt-iron alloy oxide, or a zirconium-iron alloy nitride.
In the thin film magnetic head of the invention, at least one of the first magnetic layer portion, the second magnetic layer portion, and the second magnetic layer may consist of a magnetic material containing iron, nickel, and cobalt.
A method of manufacturing a thin film magnetic head of the invention is applied to a thin film magnetic head including: a first magnetic layer and a second magnetic layer magnetically coupled to each other and having two magnetic poles facing each other with a gap layer in between near and in a recording-medium-facing surface to be faced with a recording medium; a thin film coil provided between the first and second magnetic layers; and an insulating layer for insulating the thin film coil from the first and the second magnetic layers, the first magnetic layer including a laminate of a first magnetic layer portion and a second magnetic layer portion, the first magnetic layer portion being located away from the gap layer and the second magnetic layer portion being located close to the gap layer, the second magnetic layer portion extending adjacent to the gap layer from the recording-medium-facing surface to a first position while maintaining a uniform width for defining a write track width on the recording medium, the first magnetic layer portion including a uniform width portion and a widened portion, the uniform width portion extending from the recording-medium-facing surface or its neighborhood to a second position located at or near the first position, while maintaining the same width as the uniform width of the second magnetic layer portion, the widened portion extending from the second position to a third position and having a width greater than that of the uniform width portion, the method comprises a first step of forming a first thin film coil as a part of the thin film coil in a manner that most of the first thin film coil is included in a space defined by a thickness of the uniform width portion in the first magnetic layer portion; and a second step of forming a first insulating layer portion as a part of the insulating layer, in a space defined by a thickness of the second magnetic layer portion so that the first insulating layer portion comes into contact with the first thin film coil.
In the method of manufacturing a thin film magnetic head of the invention, in a first step a first thin film coil as a part of the thin film coil is formed in a manner that most of the first thin film coil is included in a space defined by a thickness of the uniform width portion in the first magnetic layer portion and in a second step, a first insulating layer portion as a part of the insulating layer is formed in a space defined by a thickness of the second magnetic layer portion so that the first insulating layer portion comes into contact with the first thin film coil.
In the method of manufacturing the thin film magnetic head of the invention, the first magnetic layer portion may be formed so that a thickness thereof may become larger than a thickness of the first thin film coil.
In the method of manufacturing the thin film magnetic head of the invention, the second step may comprise the steps of forming a precursory-magnetic layer as a preparation layer of the second magnetic layer portion on the gap layer in an area from a position nearby which the recording-medium-facing surface is to be formed to the first position, forming a first precursory-insulating layer as a preparation layer of the first insulating layer portion to cover at least the precursory-magnetic layer and a circumference area thereof and polishing and flattening the first precursory-insulating layer until the precursory-magnetic layer is exposed, thereby forming the first insulating layer portion.
In the method of manufacturing the thin film magnetic head of the invention, when the third position in the first magnetic layer portion is located between the recording-medium-facing surface and the thin film coil and the insulating layer further comprises a second insulating layer portion covering the first thin film coil, the method further may comprise a third step of selectively forming the first magnetic layer portion at least on the precursory-magnetic layer; a fourth step of forming a second precursory-insulating layer portion as a preparation layer of the second insulating layer portion to cover at least the first magnetic layer portion and the first thin film coil; and
a fifth step of polishing and flattening a surface of the second precursory-insulating layer until the first magnetic layer portion is exposed, thereby forming the second insulating layer portion.
In the method of manufacturing the thin film magnetic head of the invention, when the first magnetic layer further comprises a third magnetic layer portion partially overlapping and magnetically coupled to the first magnetic layer portion and a fourth magnetic layer portion for connecting magnetically the first magnetic layer portion with the third magnetic layer portion, the method further may comprise a sixth step of forming the second thin film coil which is electrically connected with the first thin film coil so that most of the second thin film is included in a space defined by the fourth magnetic layer portion.
In the method of manufacturing the thin film magnetic head of the invention, the method further may comprise a seventh step of forming a recessed area by selectively etching an opposite side surface of the first insulating layer portion from the gap layer to a predetermined depth after the second step, wherein the first thin film coil may be formed on the recessed area in the first step In the method of manufacturing the thin film magnetic head of the invention, the first magnetic layer portion may be formed by plating in the third step.
In the method of manufacturing the thin filth magnetic head of the invention, the third step may comprise the steps of forming a magnetic material layer at least on the precursory-magnetic layer and patterning by selectively etching the magnetic material layer so as to form the first magnetic layer portion. In such a case, it is preferable that the first magnetic layer portion is formed using a reactive ion etching in the patterning step. Moreover, it is preferable that the patterning step is performed in a gas atmosphere containing chlorine at a temperature within a range from 50xc2x0 C. to 300xc2x0 C.
Other and further objects, characteristics and advantages of the invention will appear more fully from the following description.